1. Field of the Invention
The present invention relates to an optical component retaining device which retains an optical component such as a lens, a prism and a filter, an optical component and a housing which is suitable for retaining the optical component; and particularly relates to an optical component retaining device with which an optical component used for a view finder, a lens device and the like which are used for an electronic device such as a still camera and a video camera can be installed with high accuracy and yet with ease to the main body of an electronic device, an optical component and a housing.
2. Description of the Related Art
As a conventional optical component retaining device of this kind, there is the one described in Patent reference 1, for example. In the patent reference 1, there is a description relating to a camera in which an assembly of a finder is simplified. The camera described in this patent reference 1 includes a camera main body portion in which a photographing mechanism is assembled and a front cover and a rear cover which are assembled in such a manner as to cover this camera main body portion from the front and from the rear, respectively. In this camera, after a finder unit made of a frame body, in which a finder optical system including an objective lens and an eyepiece lens is assembled, is directly retained by either an inner surface of the front cover or that of the rear cover, the finder unit is covered with the remaining other cover to be held from the front and the rear, and the above objective lens and eyepiece lens are exposed from an objective window formed in the front cover and from an eyepiece window formed in the rear cover, respectively.
According to the camera having such structure, since the finder unit separated from the camera main body portion is held from the front and the rear by using the front cover and the rear cover constituting exterior cladding, the finder unit can be positioned directly with respect to the covers and an assembly can be performed easily in an accurate position. Further, since a projection for stably retaining the finder unit is formed on the cover side, there is effectiveness that the finder does not drop off after assembled.
Further, as another example of the optical component retaining device of this kind, there is also the one described in the patent reference 2, for example. In the patent reference 2, there is a description relating to an optical component retaining technology which is performed by using a retaining device integrally formed. The optical component retaining device described in this patent reference 2 is the one including a concave portion integrally formed, in which the concave portion has a retaining portion provided with at least a pair of parallel surfaces to retain an optical component.
According to the optical component retaining device having such structure, since the concave portion has the retaining portion provided with at least a pair of parallel surfaces to retain the optical component, an optical component having parallel lateral surfaces, for example, can reliably be held without using such means as a spring, so that the costs of components can be reduced. In addition, since the optical component can be held surely without using adhesive and the like, the optical component can easily be detached from the concave portion.
[Patent reference 1] Japanese Published Patent Application No. 2002-90852
[Patent reference 2] Japanese Published Patent Application No. 2000-214365
However, in a conventional optical component retaining device such as those described above; in the case of the former patent reference 1, since the position is determined by inserting a rib of lens into a slit portion of a housing and this housing is formed by injection molding, a draft angle has been required in the slit portion due to a structural reason of a mold of the housing. Accordingly, when the draft angle is formed on the whole surface of the slit portion to make the whole surface of an engaging portion fit and contact, there has been such a problem that corrections to a draft surface of the mold are difficult and finishing adjustment with high positional accuracy can not be performed at the time of assembly.
The above problem can be solved by using technologies such as a method of installing a lens by applying force with a spring or a method of eliminating an influence of a draft angle by making a mold of a housing into a slide structure as described in the latter patent reference 2. However, in both cases there remain such problems that the retaining device is uneconomical due to the increase in the number of components and the structure of the mold becomes complicated.
The problems to be solved by the present invention are that a conventional optical component retaining device has a large number of parts and also has the structure of a mold complicated to be uneconomical, as well as that the productivity of an optical component and a housing are not favorable.